In 27 infants with spastic bronchitis and in 23 infants with bronchopneumonia the values of IgA, IgG and IgM in bronchial secretion were determined by single radial immunodiffusion method. In both group A and B the frequencies of IgA and IgG were statistical significant. The IgM frequency was significant only in group A. The mean values of IgA and IgG were considerably higher in relation to mean IgM values. The presence of IgA and IgG was found in the first bronchial secretion sample in all investigated infants. The presence of IgM in bronchial secretion was found in high percentage. However, the presence of IgM was found in ten investigated infants only in second bronchial secretion sample. It was concluded that for estimation of real state of specific local immunity on bronchial mucosa it is necessary to determine the immunglobulin values twice and that at three days interval. In this study the local immunoglobulin deficiency was found in none case.